Duplainville (CP/CN)

Duplainville is the only place in Wisconsin where Canadian Pacific Kansas City and Canadian National cross at grade, making it a bucket-list stop for Midwest railfans. The double diamond — CP's two main tracks crossing CN's single main — sits at approximately Milepost 102.2 on the CPKC Watertown Subdivision and Milepost 102.6 on the CN Waukesha Subdivision. With roughly 53 trains per day funneling through this intersection, waits between trains are often short.

To reach the crossing, take Interstate I-94 west from Milwaukee to State Highway F (exit at Waukesha). Head north on Highway F to the third stoplight, just past a Ready Mix plant, then bear right onto Duplainville Road. The CP tracks are about three-quarters of a mile north. Park on Marjean Lane, west of Duplainville Road — do not park near the diamond itself, as CP Police actively patrol and will issue citations. To reach the CN main, continue north on Duplainville Road across the CP double main to Green Road, then head east to the tracks.

The experience is defined by the diamond: the distinctive clatter of wheel flanges hitting the frog, horns blasting at the grade crossing, and the rumble of 12,000-foot intermodals shaking the ground. Trains often slow or stop awaiting clearance, giving you extended time to study locomotive consists. It is common to see trains from both railroads converge on the crossing within minutes of each other.

Duplainville sits on flat to gently rolling terrain in Waukesha County, about 15 miles west of Milwaukee and 3 miles north of Waukesha. The immediate crossing area is a mix of light industrial buildings, scattered residential properties, and open lots along Duplainville Road. There are no dramatic elevation changes — the land is typical southeastern Wisconsin glacial outwash, sitting around 870 feet above sea level.

The surroundings feel semi-rural despite the proximity to Milwaukee's western suburbs. Pewaukee Lake, the largest lake in Waukesha County, lies about 2 miles to the northeast. In winter, the crossing area can be bitterly cold with lake-effect gusts, but snow on the ballast and frosted rail creates stark photographic contrasts. Summer brings warm, humid conditions with long daylight hours. Autumn is arguably the best season: cool temperatures, low-angle golden light, and muted foliage along the CN corridor to the north provide a classic Midwest railroad backdrop.

Two Class I railroads share this diamond, producing a combined total of roughly 53 trains per day:

CPKC (Watertown Subdivision): About 25 trains daily on the east-west double main. Traffic consists of double-stack intermodal, grain and ethanol unit trains, potash hoppers, and mixed manifest freight. Amtrak's Empire Builder (Trains 7 westbound and 8 eastbound) traverses this line twice daily. A local patrol train, CP G64, switches industrial spurs along the subdivision between Portage and Milwaukee.

CN (Waukesha Subdivision): About 28 trains daily on the north-south single main. This corridor handles heavy intermodal traffic, crude oil tank trains, lumber, frac sand unit trains from Wisconsin mines, and general manifest. Locomotive consists frequently feature CN, IC (Illinois Central heritage "Death Star" paint), BCOL, and occasional leased units. The Waukesha Sub runs 148 miles from Fond du Lac, WI south to Chicago, also hosting Metra North Central Service commuter trains on its southern segment.

The diamond was completely rebuilt in the summer of 2020 by CP and CN crews working jointly, with the old interchange track between the two railroads removed in August 2019 to create a staging area.

Vegetation near the diamond has grown significantly in recent years, limiting some formerly open sight lines. The best current vantage points:

From Duplainville Road grade crossing: The closest public viewpoint to the diamond. You can photograph trains on both the CP and CN mains from the roadside. Morning light favors eastbound CP trains (shooting west-to-east). A 70-200mm lens captures locomotive details and diamond action from here.

From Marjean Lane area: Slightly west and south, offering three-quarter views of westbound CP trains. Afternoon light works well here. Use 200-400mm lenses for tight shots of locomotive consists.

CN corridor from Green Road: Cross the CP double main on Duplainville Road and head east on Green Road to reach the CN main. This angle provides head-on or three-quarter views of northbound/southbound CN trains. Best in morning and midday light.

Be aware that all industrial parking lots near the tracks are posted No Trespassing. Stick to public roadways and road shoulders. A scanner tuned to CP Road (161.100 MHz) and CN Road frequencies is essential for predicting meets at the diamond — the real prize is capturing two trains from different railroads crossing simultaneously.

The east-west line through Duplainville was constructed in 1855 by the Chicago, Milwaukee, St. Paul and Pacific Railroad (the Milwaukee Road), running from Brookfield to Watertown and eventually extending to Portage. In 1885, the Wisconsin Central Railroad built a line south from Rugby Junction to Chicago, and the two railroads' tracks crossed at what became known as Duplainville.

In 1890, an interlocking tower was erected in the northwest quadrant of the diamond to manage the crossing. That original wooden tower burned down on January 1, 1929, and was replaced by a brick building that served the same function. When CTC (Centralized Traffic Control) was installed and the diamond began being controlled remotely from Milwaukee, the brick tower was finally demolished in 1987. An interchange connection track linking the two railroads was built in the northeastern quadrant of the diamond.

The Milwaukee Road was absorbed by the Soo Line Railroad (a CP subsidiary) in 1985, bringing the east-west line under Canadian Pacific control — now CPKC following the 2023 merger with Kansas City Southern. The Wisconsin Central went through several ownership changes, including a period under Soo Line, before CN acquired it in 2001, bringing the north-south line under Canadian National control.

On May 7, 1956, a serious passenger train accident occurred at Duplainville, one of several incidents at this busy crossing over the decades. The diamond has also been the site of numerous highway-rail crossing accidents, contributing to the installation of modern warning systems.

In the summer of 2020, CP and CN jointly rebuilt the entire diamond crossing — a major engineering undertaking that briefly shut down both main lines.

Duplainville stands out as one of the few locations in the United States where two Canadian Class I railroads cross at an at-grade diamond with public access. The CPKC-CN combination means motive power variety that you won't find on Union Pacific or BNSF territory: expect CN's black-and-red "noodle" scheme, IC heritage "Death Star" units, BCOL green, CPKC tuscan red, and frequent run-through foreign power.

The sheer volume — roughly 53 trains per day — means short waits and constant action. The double diamond configuration (CP's two mains crossing CN's single main) adds complexity: dispatchers coordinate meets, occasionally creating the spectacle of trains from both railroads crossing the diamond within moments of each other.

Unlike many urban junctions fenced off or blocked by buildings, Duplainville offers multiple public viewing angles from Duplainville Road and surrounding streets. The location also benefits from Amtrak Empire Builder service, giving passenger train fans two daily opportunities alongside the heavy freight traffic. The 2020 diamond reconstruction attracted railfan attention nationwide and was extensively documented in Trains Magazine.